Two-stage burner apparatus



April 26, 1960 G. H. SMITH TWO-STAGE BURNER APPARATUS Filed June 21,1955 u a w 8 r w. w m 0 0 vQ Q: a w 2 G m w a U ml ix i & #A, m

U a w w y 0 INVENTOR GEORGE H. SMITH By ATTORNEY V React ion ProductsTWO-STAGE BURNER APPARATUS George H. Smith, Kenmore, N.Y., assignor toUnion Carbide Corporation, a corporation of New York Application June21, 1955, Serial No. 516,959

7 Claims. (Cl. 23-277) The present invention relates to a two-stageburner for the mixing, pyrolyzing, or atomizing of fluid fuels.

It is the main object of the present invention to provide apparatus forthe rapid treatment of fuels in thermal pyrolysis reactions, such as thepyrolysis of hydrocarbons to produce acetylene. Another object is toprovide apparatus for mixing and preheating gases prior to reaction in achemical process. A still further object is to provide apparatus forpreheating and atomizing reactants which are subsequently to be employedin a chemical reaction. Other aims and advantages of the invention willbe apparent from the following description and appended claims.

In accordance with the present invention, a two-stage burner is providedhaving two successive stages separated from each other by a throatsection of reduced crosssectional area. A fluid fuel and oxidant areinjected through a mixer into the first stage. The fuel and oxidantmixture is burned in the first stage and the hot products of combustionare discharged through the communicating throat section to the secondstage. Concurrently therewith, a fluid or fluidized stock to be treatedis introduced into the second stage wherein it is heated and atomized orpyrolyzed by contact with the hot products of combustion from the firststage. Factors determining which of these three effects are producedinclude the manner in which the fluid stock is introduced into thesecond stage and the composition of the stock introduced.

The single figure of the drawing is a longitudinal crosssectional viewof a burner embodying the invention and adapted primarily for use in thepyrolysis of hydrocarbons to produce other hydrocarbons, such asacetylene.

Referring specifically to the drawing, burner B is provided havingaxially aligned members 10, 12, 14, 16 and 18, successively positionedfrom the rear toward the forward .end of the burner. Member is awater-cooled mixer member having an axially-positioned stepped internalboring passing therethrough and provided with threads 20 at the upperend thereof adapted to receive andengage an injector member 22 therein.The internal boring is provided with a frusto-conical portion 24 adaptedto cooperate with the outer surfaces of injector 22 to form a conicalshaped annular passage 26 therebetween. A throat section 28 in whichmixing of the gases takes place is preferably provided downstream of thefrusto-conical portion 24. The internal boring of mixer member 10terminates at the lower end in a threaded'circula-r portion 30 adaptedto engage the upper end of member 12.

Member 12 contains the first stage of the two-stage burner, and has aninternal chamber 32 of substantially constant diameter dischargingthrough a'reduced-diameter throat section 34 positioned at the lower endthereof in member 14. Member 12 is secured to member 14 by threads 36.Member 16, containing internal chamber 40 of substanthrough fluidconduit 56, communicating annular pasidentical to member *12 and issecured to member 14 by threads 42.

Member 18, secured to the lower end of member 16 by threads 44, containsan internal passage 46 of substantially constant cross-sectional areainto which a quenching fluid is introduced in multiple radial spraysthrough ports 50. The discharge end 52 of passage 46 is connected to agas collector (not shown) when the two-stage burner is employed for thepyrolysis of saturated hydrocarbons to produce other hydrocarbons, suchas acetylene. The quenching fluid is introduced into member 18 sage 58,and discharging through the multiplicity of radially-positionedquenching fluid ports 50 opening into the internal passage 46 of member18.

It is, of course, to be understood that, when the twostage burner of theinvention is employed in other than a pyrolysis process, member 18 maybe removed from the burner, since quenching fluid introduction is nolonger necessary.

Conduit 60 is provided in block 14 for the introduction of stock to thesecond stage of the burner. This stock comprises the fluid to be heated,and pyrolyzed or atomized in the second stage, depending upon theoperation to be performed.

Injector member 22 comprises a centrally-positioned oxidant conduit 70communicating at the lower end thereof with a plurality of radiallydisposed oxidant metering ports 72 positioned to discharge oxidant athigh velocity transversely to the annular metering passage 26 formedbetween the lower surface of injector 22 and frusto-conical side walls24 of the internal boring of member 10. A longitudinal fuel gas conduit74 is eccentrically-positioned in injector 22 and discharges into theannular chamber 76 formed between injector 22 and the internal boringmixer member 10. Chamber 76 communicates with conical annular passage 26so that a stream of fuel gas is fed therethrough past the discharge endsof oxidant ports 72. The streams of fuel gas and oxidant then passthrough throat section 28 of the mixer at very high velocity; andintimate mixing is achieved between these gases, which are then passedto the first stage 32 of the burner. It has been found preferable,regardless of the specific fuel and oxidant employed, to introduce thegas having the large volume through passage 26 of the mixer, while thegas having the smaller volume is passed through metering ports 72.

It has been found that by maintaining the pressures across oxidant ports72 at a ratio of greater than 2:1 (inlet pressure-to-outlet pressure) anoxidant stream discharge velocity at or near sonic velocity can beattained. In this manner, mixing takes place at or near sonic velocityand intimate mixing is achieved by the time combustion of the mixture isinitiated in the first stage 32 of the burner.

Thus, the cross-sectional area of the metering ports and the pressuredrops across them are so selected as to provide for impingement of thestreams of fluid fuel and oxidant at a velocity greater than Mach numberof 0.5 and preferably at about a Mach number of 1.0.

As employed herein the term Mach number refers to the ratio of thelinear gas velocity of the mixture to the velocity of sound in the samemixture for the given temperature and gas composition.

Upon combustion in the first stage of the burner, hot combustionproducts are discharged through throat section 34 into the second burnerstage 40. The fuel and tially constant cross-sectional area, issubstantially oxidant are introduced into the first stage insubstantially stoichiometric proportions and the fluid stock introducedinto the second stage is heated by-the hot products of combustionentering the stage through throat 34.

Patented Apr. 26, 1960 In addition, if a liquid stock is employed, thestock is atomized to a fine spray which passes with the hot combustionproducts at a very high velocity from the second stage 49. Under theseconditions, the burner operates pose if exposed to the hot combustionproducts for too long a period of time, and the hydrocarbon yield willbe reduced if the time is too short. For example, in the production ofacetylene by the pyrolysis of methane, in order to prevent undueacetylene decomposition it is desirable that the reaction products bequenched within less than four milliseconds after the initiation of thepyrolysis reaction.

The hot products of combustion passing from the first stage 32 passthrough throat section 34 and into the second stage at at a velocitygreater than 0.5 Mach number, and preferably 1.0 Mach number, due to thepressure drop maintained across the throat section. Therefore, the stockintroduced into the second stage is introduced into a high-temperature,high-velocity (approximately 3000 fps.) stream, and the treatment of thestock (whether it be preheating, atomizing, or pyrolyzing) isaccomplished at high velocity and, consequently, at short intervals oftime. applications of the burner. Where preheating alone is effected,the stock is preheated and discharged from the burner to the point ofdesired use before any substantial quantity of preheat is lost byconduction through the side walls. Where atomization of a hot stream ofstock is effected, this is accomplished and the atomized stream isdischarged from the burner to the point of desired use before heat lossor a settling out of the atomized spray can occur. And Where pyrolysisof the stock is the application, this result can be accomplished and thereaction products quenched, in short intervals of time, be-

This result is very beneficial-in all employed to produce productscontaining in excess of 7 vol. percent of acetylene in the pyrolysis ofmethane by the method described and claimed in my application entitledHydrocarbon Pyrolysis, Serial No. 516,957, filed June 21, 1955. Inaddition, apparatus embodying the present invention has beensuccessfully employed to atomize fuel for introduction into furnaces ofthe openhearth type, as described and claimed in my application entitledMethod and Apparatus for Heating of Industrial Furnaces,-Serial No.610,553, filed September 18, 1956. 1

What is claimed is:

1. A burner of the internal combustion type comprising an internalcombustion chamber; a processing chamber; a constricted throat sectioncommunicating between said internal combustion chamber and said processchamber for introducing the hot products of combustion from saidcombustion chamber into said processing chamber,

said constricted throat section having a cross-sectional area such thatthe products of combustion from said internal combustion chamber entersaid processing chamber at substantially sonic velocity; inlet means forintroducing a stream of fluid fuel and oxidant mixture in substantiallystoichiometric proportions into said combustion chamber to burnsubstantially completely therein, said inlet means comprising separatesupply conduits for fuel and oxidant terminating in metering passagesadjacent the in-- let of said internal combustion chamber, said meteringpassages each having cross-sectional area smaller than the supplyconduit therefor to form and impinge streams of fuel and oxidant at highvelocity into sudden mixing engagement with each other at a substantialangle of impingement such that the fluid fuel and oxidant mixture foreextensive decomposition of the unsaturated hydrocarbons produced canoccur.

Injector member 22 is provided with passages for the circulation of acooling fluid, such as Water. The cooling fluid is introduced throughconduit 80 to boring 82 dis-- charging into annular space 84,surrounding oxidant inis formed and introduced into said internalcombustion chamber at a velocity greater than 0.5 Mach number; and meanspositioned in said processing chamber in the vicinity of the juncture ofsaid constricted throat section and said processing chamber forintroducing a stream of fluid stock into said substantially sonicvelocity stream of hot combustion products entering said processingchamber from said constricted throat section.

2. A burner in accordance with claim 1, wherein the walls of saidinternal combustion chamber, said constricte'd throat section and saidprocessing chamber are composed of a refractory material, and the wallsof said internal combustion chamber and said processing chamber areelongated thick walled sections of substantially constant internaldiameter.

let conduit 70, and is discharged therefrom through boring 86 to outletconduit 88. Mixer member 10 is similarly provided with cooling waterthrough conduit 90 communicating, in turn, with radial boring 92,annular space 94, radial boring 96 and water discharge conduit 93.Member 14 is also provided with cooling water from inlet conduit 104)communicating, in turn, with radial boring 16 2, annular space 104,radial boring 106 and cooling water discharge conduit 108.

Portions of the burner of the embodiment of the drawing are constructedof refractory material. The two-stage members, 12 and 1d are constructedof refractory sections 110 and 112, respectively, lined with internalsleeves 114 and 116, respectively, suitably composed of metal ceramicmaterials such as disclosed in U.S. Patent 2,698,990. In addition,constricted throat section 34 is suitably composed of such metal ceramicmaterial. Outer sleeves 120 and 122, respectively, are provided aroundthe outside of the refractory material and serve to secure thestage-members to the adjoining members of the burner.

Larger scale burners have also been made with metallic liners providedwith water cooling. Such construction has been found to be satisfactorysinceas the size is increased the ratio of wall area to volume decreasesand thus the percentage heat loss through the walls also decreases. p p

The apparatus of the invention has been successfully 3. A burner inaccordance with claim 1, wherein said inlet means for introducing saidstream of fluid fuel and oxidant mixture to said combustion chambercomprises a Water-cooled metal mixer having a frusto conical entrance,and an injector having a portion forming with said entrance a mixingpassage in which said sudden mixing engagement takes place, and saidmixer has a depending flange receiving the top of said refractory linedsection of said internal combustion chamber wall.

4. A burner of the internal combustion type comprising an internalcombustion chamber; a processing chamher; a constricted throat sectioncommunicating between said internal combustion chamber and said processchamher for introducing the hot products of combustion from saidcombustion chamber into said processing chamber, said constricted throatsection having a cross-sectional area such that the products ofcombustion from said internal combustion chamber enter said processingchamber at a velocity greater than 0.5 Mach number; inlet means having acentral oxygen passage and an annular fuel chamber surrounding the same,and a converging inlet to, a throat leading to said internal combustionchamber to form a metering passage receiving fuel from said annularchamber, and radiating oxygen passages from said central oxygen passageinto said metering passage for introducinga stream of fluid fuel andoxidant mixture in substantially stoichiometric proportions into saidcom bustion chamber to burn substantially completely therein, said inletmeans having cross-sectional area such that the fluid and oxidantmixture is formed and introduced into said internal combustion chamberat a velocity greater than 0.5 Mach number; and means positioned in saidprocessing chamber in the vicinity of the juncture of said constrictedthroat section and said processing chamber for introducing a stream offluid stock into said stream of hot combustion products entering saidprocessing chamber from said constricted throat section.

5. A burner in accordance with claim 4, wherein the walls of saidinternal combustion chamber, said constricted throat section and saidprocessing chamber are composed of a refractory material and the wallsof said internal combustion chamber and said processing chamber aresubstantially identical sections lined with metal ceramic sleeves ofsubstantially constant internal diameter.

6. A burner in accordance with claim 4, wherein said inlet means forintroducing said stream of fluid fuel and oxidant mixture to saidcombustion chamber comprises a water-cooled metal mixer in which saidannular fuel chamber, converging inlet and metering passage are formed,and an injector in which said central oxygen passage and radiatingoxygen passages are formed.

7. In a burner for hydrocarbon pyrolysis having means for quenching thehot pyrolysis products and means for collecting said quenched pyrolysisproducts and separating the components thereof, an internal combustionchamber, and a processing chamber; a constricted throat sectioncommunicating between said internal combustion chamber and said processchamber for introducing the hot products of combustion from saidcombustion chamber into said processing chamber, said constricted throatsec tion having a cross-sectional area such that the products ofcombustion from said internal combustion chamber enter said processingchamber at substantially sonic velocity; inlet means having a centraloxygen passage and an annular fuel chamber surrounding the same, and aconverging inlet to a throat leading to said internal combustion chamberto form a metering passage receiving fuel from said annular chamber, andradiating oxygen passages from said central oxygen passage into saidmetering passage for introducing a stream of fluid fuel and oxidantmixture in substantially stoichiometric proportions into said combustionchamber to burn substantially completely therein, said inlet meanshaving crosssectional area such that the fluid fuel and oxidant mixtureis formed and introduced into said internal combustion chamber at avelocity greater than 0.5 Mach number; and means positioned in saidprocessing chamber in the vicinity of the juncture of said constrictedthroat section and said processing chamber for introducing a stream offluid stock into said substantially sonic velocity stream of hotcombustion products entering said processing chamber from saidconstricted throat section, said fluid stock being thereby pyrolyzed bymeans of said stream of hot combustion products.

References Cited in the file of this patent UNITED STATES PATENTS1,828,784 Perrin Oct. 27, 1931 2,419,565 Krejci Apr. 29, 1947 2,495,665Spring Jan. 24, 1950 2,659,662 Heller Nov. 17, 1953 2,719,184 Kosbahn etal Sept. 27, 1955 2,790,838 Schrader Apr. 30, 1957

1. A BURNER OF THE INTERNAL COMBUSTION TYPE COMPRISING AN INTERNAL COMBUSTION CHAMBER, A PROCESSING CHAMBER, A CONSTRICTED THROAT SECTION COMMUNICATING BETWEEN SAID INTERNAL COMBUSTION CHAMBER AND SAID PROCESS CHAMBER FOR INTRODUCING THE HOT PRODUCTS OF COMBUSTION FROM SAID COMBUSTION CHAMBER INTO SAID PROCESSING CHAMBER SAID CONSTRICTED THROAT SECTION HAVING A CROSS-SECTIONAL AREA SUCH THAT THE PRODUCTS OF COMBUSTION FROM SAID INTERNAL COMBUSTION CHAMBER ENTER SAID PROCESSING CHAMBER, AT SUBSTANTIALLY SONIC VELOCITY, INLET MEANS FOR INTRODUCING A STREAM OF FLUID FUEL AND OXIDANT MIXTURE IN SUBSTANTIALLY STOICHIOMETRIC PROPORTIONS INTO SAID COMBUSTION CHAMBER TO BURN SUBSTANTIALLY COMPLETELY THEREIN, SAID INLET MEANS COMPRISING SEPARATE SUPPLY CONDUITS FOR FUEL AND OXIDANT TERMINATING IN METERING PASSAGES ADJACENT THE INLET OF SAID INTERNAL COMBUSTION CHAMBER, SAID METERING PASSAGE EACH HAVING CROSS-SECTIONAL AREA SMALLER THAN THE SUPPLY CONDUIT THEREFOR TO FORM AND IMPINGE STREAMS OF FUEL AND OXIDANT AT HIGH VELOCITY INTO SUDDEN MIXING ENGAGEMENT WITH EACH OTHER AT A SUBSTANTIAL ANGLE OF IMPINGEMANE SUCH THAT THE FLUID FUEL AND OXIDANT MIXTURE IS FORMED AND INTRODUCED INTO SAID INTERNAL COMBUSTION CHAMBER AT A VELOCITY GREATER THAN 0.5 MACH NUMBER, AND MEANS POSITIONED IN SAID PROCESSING CHAMBER IN THE VICINITY OF THE JUNCTURE OF SAID CONSTRICTED THROAT SECTION AND SAID PROCESSING CHAMBER FOR INTRODUCING A STREAM OF FLUID STOCK INTO SAID SUBSTANTIALLY SONIC VELOCITY STREAM OF HOT COMBUSTION PRODUCTS ENTERING SAID PROCESSING CHAMBER FROM SAID CONSTRICTED THROAT SECTION. 